This invention relates providing reverse voltage and over-voltage protection for circuits and systems. In particular, vehicle systems subject to accidental reverse polarity voltage applications and over-voltage conditions resultant from load removal and the like. For example, in vehicle systems where integrated circuit microcontrollers are interfaced with motors via MOSFET(s) for motor position controllers such as may be employed in vehicle steering systems. Such systems may use control electronics to provide the interface between low voltage microcontrollers and the high voltage MOSFETs. The control electronics may also include motor control logic, a charge pump, MOSFET gate drives and overvoltage and overcurrent protection.
Unfortunately, many electronic systems include components that can be susceptible to voltage transients on their supply voltage. Such transients in certain circumstances may even destroy the components leading to early failure and excessive repairs. Another option to protect such electronics modules from transients and reverse voltage would be to use transient suppression devices to limit the voltage below the maximum input voltages for the devices. Unfortunately, if there were a great amount of energy in the transient pulse, the transient suppression devices would be very large and expensive. Therefore, it would be beneficial to provide a cost effective means of protecting high side circuits from reverse and over voltage transients.